When trying to create a headless Vulkan instance without a display device available, device enumeration would fail. Part of the physical device creation code already accounts for a missing display device, allow device enumeration to continue in that case too so headless instances can be created. Signed-off-by: Erico Nunes <nunes.erico@gmail.com> Reviewed-by: Iago Toral Quiroga <itoral@igalia.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25313>